Simplified model for the non-linear behaviour representation of reinforced concrete columns under biaxial bending

In the present paper a simplified model is proposed for the force-deformation behaviour of reinforced concrete members under biaxial loading combined with axial force. The starting point for the model development was an existing fixed-length plastic hinge element model that accounts for the non-linear hysteretic behaviour at the element end-sections, characterized by trilinear moment-curvature laws. To take into account the section biaxial behaviour, the existing model was adopted for both orthogonal lateral directions and an interaction function was introduced to couple the hysteretic response of both directions. To calibrate the interaction function it were used numerical results, obtained from fibre models, and experimental results. For the parameters identification, non-linear optimization approaches were adopted, namely: the gradient based methods followed by the genetic, evolutionary and nature-inspired algorithms. Finally, the simplified non-linear model proposed is validated through the analytical simulation of biaxial test results carried out in full-scale reinforced concrete columns

Historic Appraisal Review and Geometric Characterization of Old Masonry Buildings in Lisbon for Seismic Risk Assessment

The Metropolitan Area of Lisbon (MAL) has the highest population and building density in Portugal, and is exposed to medium to high magnitude earthquakes due to its geographical location. Currently, the MAL housing stock is constituted by approximately 35% of masonry residential buildings with a large variability of materials and construction techniques, as a result of many centuries of history. Most of these buildings were built before the introduction of the first design code for building safety against earthquakes (RSSCS) in Citation1958 and therefore were only designed to support gravity loads. Given the presence of these buildings in areas of significant seismicity, a comprehensive research is needed to assess the seismic risk and define mitigation policies for this population of unreinforced masonry buildings. The main purpose of this work is thus to geometrically characterize these typologies, through an exhaustive survey of dozens of masonry buildings collected from original drawings and identify the most important aspects that can influence their seismic behavior. After a compressive historical background, the information collected is statistically analyzed and expressed through probability distributions that can be used for the development of numerical models and derive seismic vulnerability functions, fundamental to conduct seismic risk analyses.info:eu-repo/semantics/publishedVersio

O desafio da previsão do comportamento fora-do-plano de edifícios existentes de alvenaria

O comportamento sísmico de estruturas existentes em alvenaria é muito condicionado pelo seu comportamento fora-do-plano, originando os chamados mecanismos locais, existindo diversas metodologias que tentam prever o comportamento deste tipo de estruturas e/ou modos de colapso. Este trabalho pretende resumir os principais resultados obtidos num evento subordinado ao tema “Methods and challenges on the out-of-plane assessment of existing masonry buildings”, inserido na 9th IMC (2014) em Guimarães, com o objectivo de prever o comportamento de duas estruturas em alvenaria utilizando métodos de análise correntemente utilizados na análise sísmica de estruturas existentes. Relativamente às estruturas estudadas, uma destas era materializada em alvenaria tradicional de pedra de dois panos, sendo a outra construída em alvenaria de tijolo. Estas estruturas foram ensaiadas à escala real na mesa sísmica do LNEC. No final do presente artigo apresentam-se os principais resultados obtidos com as simulações realizadas e sua comparação com o comportamento real das estruturas.The seismic behaviour of existing masonry buildings is governed by the out-of-plane behaviour in the form of the so-called local mechanisms. Despite recent advances within the area, there are several different methodologies to predict the behaviour of these local mechanisms. The article herein submitted aims to present the main results obtained on a workshop entitled “Methods and challenges on the out-of-plane assessment of existing masonry buildings”, within the 9th IMC (2014) held at Guimarães, with the objective of predict the behaviour of masonry structures making use of any available method for the seismic analysis. Regarding the studied structures, one was built on traditional doubleleaf stone masonry while the other was built on brick masonry, and they were tested at LNEC shaking table. The main conclusions are presented at the end of the article, namely the obtained results with the prediction and the observed experimental behavior

Experimental analysis of brick masonry veneers walls under out-of-plane loading

The evaluation of seismic vulnerability of existing buildings with masonry veneer systems has been recog-nized as a major problem because of the large number of buildings constructed before the development of rational seismic codes. This resulted in the construction of masonry veneers without reference to the design to seismic action and adequate constructive detailing. In order to contribute to increasing of knowledge about seismic behaviour of brick veneer walls, an experimental campaign was developed on testing quasi-statically full-scale systems under in-plane and out-of-plane loading. This paper describes in detail the out-of-plane performance of a constructive system characteristic of Portugal and South of Europe, constituted of brick masonry veneer leaf connected to an infill wall inserted in a reinforced concrete (rc) frame. A descrip-tion of the test setup for the out-of-plane tests is provided and the main results, including the damage pat-terns and force displacement diagrams, are presented and discussed.The authors acknowledge the support of the Portuguese Foundation for Science and Technology (FCT), through the financing of the research project SEVen - Development of Sustainable Ceramic Brick Masonry Veneer Walls for Building Envelops (PTDC/ECI-CON/30876/2017)

Levantamento de nematóides fitoparasitas associados a pomares de videira em declínio da serra gaúcha.

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Tuned liquid dampers simulation for earthquake response control of buildings

This paper is focused on the study of an earthquake protection system, the Tuned Liquid Damper (TLD), which can, if adequately designed, reduce earthquake demands on buildings. This positive effect is accomplished taking into account the oscillation of the free surface of a fluid inside a tank (sloshing). The behaviour of an isolated Tuned Liquid Damper, subjected to a sinusoidal excitation at its base, with different displacement amplitudes, was studied by finite element analysis. The efficiency of the TLD in improving the seismic response of an existing building, representative of modern architecture buildings in southern European countries was also evaluated based on linear dynamic analyses

Experimental study on the mechanical performance of steel ties for brick masonry veneers

Publicado em "Brick and block masonry: trends, innovations and challenges. ISBN 978-1-138-02999-6An experimental study was carried out to analyse the tension and compression behaviour of wall ties anchoring brick veneer walls to masonry infill walls as the backing support. Connection subassemblies were tested under monotonic and cyclic loading, simulating out-of-plane loading of veneer wall systems in order to understand the influence of six different ties with different design, thickness and attachment methods in the strength, stiffness and failure modes of the connection system. Experimental results from this study show more details about the behaviour of this system and importance of determined parameters. Tensile resistance capacity can be more influenced by wall tie design, while tie thickness was considered to be the most important parameter in compression behaviour. Attachment methods studied do not considered a very influential factor. This study can help to understand and justify the contribution of these elements for the mechanical masonry veneer walls under different loading conditions.Portuguese Science and Technology Foundation (FCT) - grant SFRH/BD/96484/2013FCT (Portuguese Foundation for Science and Technology), within ISISE, project UID/ECI/04029/201

Principais lições de um projeto agroflorestal com pequenos produtores no Baixo Rio Negro (Amazonas).

O projeto "Implantação de sistemas agroflorestais com pequenos produtores da Amazônia Central" teve por objetivo adaptar tecnologias agroflorestais às condições de pequenas comunidades do Baixo Rio Negro, Amazonas. Neste trabalho são relatados os primeiros cinco anos do projeto e as principais lições aprendidas, importantes para outros projetos que abordem a questão agroflorestal em propriedades rurais

Internal devaluation and economic inequality in Portugal: challenges to industrial relations in times of crisis and recovery

Internal devaluation policies imposed in southern European countries since 2010 have weakened labour market institutions and intensified wage inequality and the falling wage share. The debate in the wake of the financial and economic crisis raised concerns about slow wage growth and per- sistent economic inequality. This article attempts to shed light on this debate, scrutinising the case of Portugal in the period 2010–2017. Mapping the broad developments at the national level, the article examines four sectors, looking in particular at the impact of minimum wages and collective bargaining on wage trends vis-a`-vis wage inequality and wage share trajectories. We conclude that both minimum wage increases and the slight recovery of collective bargaining had a positive effect on wage outcomes and were important in reducing wage inequality. The extent of this reduction was limited, however, by uneven sectoral recovery dynamics and the persistent effects of pre- carious work, combined with critical liberalisation reforms.info:eu-repo/semantics/acceptedVersio